Products for and methods of quenching to harden steels



United States Patent Qfilice A 2,799,606 Patented July 16, 1957 PRODUCTS FOR AND METHODS OF QUENCHING TO HARDEN STEELS Michael W. Freeman, Detroit, Mich.

N Drawing. Application February 23, 1954, Serial No. 412,080

24 Claims. (Cl. 148-18)' This invention relates to quenching metals, to quenching mediums for use in such quenching methods, and to the resulting quenched metals themselves, In producing metals which are more uniform in character, of

increased hardness, toughness, and ductility as compared with metals quenched by prior art methods, particularly utilizing compositions having as components, phosphorus and sulfur containing organic compounds.

Although various practices have been developed in the metal art for imparting hardness and strength to metals, one of the most important is quenching of heattreated metals from above their critical temperature in liquid mediums. The quenching operation essentially involves immersing metals which have been heat-treated above the critical temperature of the metal, into suitable quenching medium in order to establish certain improved physical structures in the metal as uniformly as possible, upon which the hardenability and strength of the metal depend, and without setting up great internal stresses and strains in the metal, so as to avoid the possibility of distortion, warping, and, in some cases, even cracking of the quenched metal.

Hardenability is imparted to metals when rapidly cooled from above their critical temperature so as to allow the transformation of the physical structure of the metal. In connection with steels for example, there is the transformation of the physical structure of the metal from austenite and cementite, which is a composition of iron and carbon dissolved in austenite, into hard martensite and other hard structures. This transformation should be conducted at as low a temperature as possible and in the shortest time interval, and having attained this range, the heat transfer from the metal surface to the liquid medium should be as continuous and uniform as possible in order to obtain metals of greater and more uniform hardenability. With slow cooling, carbide precipitates from austenite during transformation into ferrite to give a soft pearlite structure. However, when metals are rapidly cooled, the carbide does not precipitate out and most of it is held in solid solution in the transformed austenite into martensite or other hard structures. A principal object of quenching, therefore, is to produce these physical transformations without distortion, warping, or setting up such great internal stresses in the metal as would result in cracking, and at the same time obtain maximum and as nearly as possible uniform hardenability in the metal.

The conventional art of quenching heat-treated metals from above their critical temperature in order to induce hardenability by means of water and other mediums such as brines and caustic soda solutions, is a well established practice. Although quenching heated metals in aqueous mediums imparts maximum hardenability, warping, distortion, brittleness, uneven hardness, and even cracking of the metals frequently occur. These disadvantages apparently are caused by pockets formed by vapors of the solution or by its condensationon the quenched object which create marked differentials in the hardness of the metal surface. These areas may either be localized or generally diffused. The vaporous interface which forms between the metal surface and quenching medium acts as an insulator, thus preventing uninterrupted desired rate of heat flow from the metal surface into the liquid medium. This vaporous insulating interface inhibits heat diffusivity from the core of the metal through the hardened metal surface into the liquid medium, thus trapping the heat in the metal and cansing a slower rate of cooling, which results in different physical structure formation from that formed at the rapidly cooled surface. Such uneven cooling process produces metals having hardnesses which are not uniform throughout the metal or even at its surface and which causes brittleness in isolated areas or even over the whole area. In addition, drastic aqueous quenching results in warping, distortion, and cracking of the metal thus treated.

Oil emulsions or various oils such as fish and marine oil, animal oils, mineral oils, and their mixtures, have supplanted aqueous quenching mediums in alleviating the defects generally produced in metals by aqueous quenching. Although quenching oils and oil emulsion mixtures in part relieve the internal stresses formed during hardening, and although brittleness is reduced, metals quenched in such mediums are usually softer than those quenched in aqueous mediums, since the quenching speed of such compositions is substantially slower, thus inhibiting or retarding the formation of hard martensite, spheroids and other hard structures. Furthermore, as in connection with aqueous quenching mediums, a persistent vaporous interface forms between the metal and the liquid, which acts as an insulator and retards the flow of heat from the surface of the metal into the liquid. In addition, oil and/or oil emulsions tend to oxidize, form sludge, thicken, break down, and decompose at elevated temperatures, which greatly decrease the life of the compositions, make it troublesome to use, and produce results which are not uniform.

Among the objects of the present invention is the development of methods for quenching metals which give the desired improved properties as to hardness, etc., and reduce the defects of prior art quenching methods to a minimum.

Further objects include the production of mediums which enable such quenching operations to be carried out.

Further objects include quenching mediums having a rapid initial cooling rate and thereafter a uniform and continuous rate of cooling, so as to produce a metal of improved hardness, ductility, and strength, etc.

Further objects include the production of oil and oil emulsion quenching mediums which effect greater and more uniform hardness in metals than any known commercial oil composition and which approach the hardnesses in metals which result from aqueous quenching.

Further objects include oil and oil' emulsion quenching compositions which are highly stable over wide temperature variations and long periods of use and which are not corrosive to the metal with which they are in contact, but rather act as corrosion inhibitors.

Still further objects and advantages of the present invention will appear from the more detailed description set forth below, it being understood that this more detailed description is given by way of illustration and explanation only, and not by way of limitation since various changes therein may be made by those skilled in the art without departing from the scope and spirit of the present invention.

In accordance with the present invention metals are quenched in a quenching medium containing a minor amount of a reaction product of a phosphorus sulfide and an organic sulfonate; Individual organic sulfonates or complex mixtures'of organic sulfo compounds may be utilized. The reaction products are desirably employed in mediums of oil and/ or water and/or emulsions of oil and water. The quenching medium may be so prepared as to have either oil or water as its continuous phase. The phase selected will have an effect upon the ultimate maximum physical properties of the quenched metal. Generally an object quenched in water is much harder and more brittle than the same object quenched in oil. However, with a combination of oil in water or water in oil emulsions, the desirable properties may be enhanced Without the disadvantageous features. To such compositions various additives may be incorporated for producing particular effects, more particularly fatty acids and/ or organic amines or combinations of fatty acids and organic amines or reaction products of phosphorus sulfides with any of these components or mixtures thereof, may be added to these compositions to impart beneficial effects to the quenching medium as well as to the metal treated.

The organic sulfonate employed may be aliphatic, aromatic, heterocyclic, or mixtures of any of these various organic sulfonates. A particularly desirable sulfonate that may be employed in accordance with the present invention includes the sulfonates derived from treatment and purification of petroleum oils with sulfuric acid. The conventional method of recovering sulfonates as by-products during the refining of petroleum distillates is to dilute the sludge with a hydrocarbon oil. The mahogany acids remain in the resulting oil layer and are separated from the sludge layer which contains the green acids. The oil layer can be washed with aqueous alcoholic solutions which remove the mahogany acids; or it may be treated with alkali and the sulfonic acids recovered with alcohol as mahogany salts. The sludge may be boiled with Water and the dilute acid recovered. The supernatant layer may then be neutralized and the residual oil extracted with naphtha, or other suitable solvent or method for producing the organic sulfonate. The neutralized sulfonate is purified by washing with acid or extraction with alcohol, or in any other suitable manner. The sulfonates thus formed are commonly referred to in the art as mahogany sulfonates, and various salts of such sulfonates such as the alkali, alkaline earth, and heavy metal salts of petroleum sulfonic acids, water or oil-soluble, may be utilized in accordance with the present invention.

Other desirable sulfonates that may be employed include esters of sulfo-dicarboxylic acids, polyalkylated naphthalene sulfonates, polyalkylated naphthalene sulfonateformaldehyde condensation products, polyalkylated diphenylsulfonates, higher sulfated secondary alcohols, higher alkyl sulfated alcohols, sulfonated castor oil, sodium taurocholate, etc. For example, the following compounds have been found satisfactory: the esters of sulfo-succinic acid, formaldehyde condensation products of di-isopropylated naphthalene B sulfonic acid, di-secondary butyl naphthalene sulfonate, sodium tetrahydronaphthalene B sulfonate, organic petroleum sulfonates, etc. In illustrating the invention below, the mahogany sulfonates will be utilized since they are readily available and are less expensive, and therefore, are desirable in producing quenching mediums in accordance with the present invention.

Various types of oils may be utilized in compounding the quenching mediums of the present invention, particularly petroleum oils, petroleum oil fractions-and petroleum oil distillates. Mineral oils of various types having relatively high flash and fire points, and that are substantially heat and sludge resistant and may be used as diluents for the quenching bases of this invention. Such oils, for example, may be of the naphthenic or paraflinic type, and desirably have'a viscosity at 100 F. of from 50 to 1000 S. U. V.

Organic amines per se or their reaction products with phosphorus sulfides that may be added to the quenching mediums may be any type of organic amine including aliphatic, aromatic, carbocyclic, alicyclic, and heterocyclic amines, among which may be mentioned alkylamines, alkyl polyamines, alkylolamines, polyalkylene polyamines, alicyclic amines, aralkylamines, heterocyclic basic nitrogen compounds, etc. Representative examples of such amines are diethylamine, monoamylamine, di-amylamine, and tri-amyl amine, di-n-butylamine, monobutylamine, undecyclic amine, lauryl amine, myristicamine, palmitylamine, stearylamine, mono-, di-, and tri-ethanolamine, quaternary ammonium compounds, laurylolamine, palmitylolarnine, stearylolarnine, ethylene diamine, diarnino-isopropanol, triethylene tetramine, cyclohexylamine, dicyclohexylamine, benzylamine, morpholine, piperidine, pyridine, quinoline, cephalin, lecithin, etc., as well as materials like Alkaterge-O.

Fatty acids per se or their reaction products with phosphorus sulfides that may be employed are the higher fatty acids both saturated and unsaturated, particularly those that may be produced or obtained from vegetable and animal glycerides and they may be used as individual fatty acids or as complex mixtures thereof as derived by the saponification of the oils and fats, exemplary acids and mixtures including oleic, myristic, lauric, undecyclic, stearic, palmitic, ricinoleic, abietic, linoleic, peanut-oil fatty acids, soya bean oil fatty acids, hydrogenated soya bean oil fatty acids, hydrogenated fish oil fatty acids, blown and boiled acids, etc., or the phosphorus sulfide reaction products with any of these acids or mixtures thereof. Abietic acid is exemplary of the acids obtainable from natural resins including rosin, etc., and may also be used as such or in hydrogenated condition, or as a phosphorus sulfide reaction product, or mixed with fatty acids, etc., or their phosphorus sulfide reaction products.

Various mixtures of the reaction products of phosphorus sulfides with organic sulfo compounds admixed with fatty acids and/ or their reaction products with phosphorus sulfides, or amines when desired, and diluted with mineral oil or reaction products of mineral oil fractions with phosphorus sulfides or formed into emulsions have been found to possess the unusual property of cooling heat-treated metals rapidly initially so as to establish those physical structures in the metal which impart maximum hardness, ductility, and strength, as well as subsequent slower but uniform cooling which reduces to a minimum internal stresses caused by the quenching operation. Compositions of this invention possess the combined desired properties of aqueous and oil quenching mediums and more ideally approach these properties than any known quenching material as illustrated hereinafter.

The unusual quenching properties of sulfur-phosphorated organic sulfo containing quenching mediums appear to be due to the initial high heat absorptive capacity of such mediums, which causes an extremely rapid cooling of the metal, resulting in great hardness and sharply reducing resistance to unit heat flow. This reduction may be due partly to elimination of an insulation film and/ or improvement in the metal-to-medium interface, minimizing stresses and strains in the metal. The liquid medium of this invention and the surface of the metal approach a state of solid-liquid continuous relationship throughout the quenching time. This appears to be due to a chemical or physio-chemical reaction which takes place on the metal surface, bringing about a nearly continuous phase resulting in an almost uninterrupted rate of heat flow from the heated metal into the cooler quenching mediums of this invention. Thus, by maintaining this phase relationship, heat continues to be lost at the surface of the metal at a rate proportional to the difference in temperature between the surface of the metal and cooler quenching medium, resulting in more uniform and harder metal. Regardless, however, of Whether these explanations theoretical or otherwise, may be the explanation as to why the improvements take place, unique results have been obtained in practice in utilizing the quenching mediums of the present invention.

The following examples will illustrate the invention and the unusual improved results obtained, quenching compositions that may be employed in accordance with the present invention and their comparison with known prior art types of quenching mediums. The proportions, type of sulfonate used, as well as other additives mentioned in the examples given below are not to be construed as limitations. The examples illustrate wide ranges of mixtures, proportions, and applicability of quenching mediums of this invention.

In these examples, the invention is particularly illustrated by its application to the improvement in properties of steels. While various metals may be treated, the application of the invention to steels particularly illustrates the unique results obtained. The steel treated may be of any desired type such as those known in the art as NE 8630, NE8650, SAE 1065 steels, SAE 1010, SAE 4065, SAE 4067, 6322, 6150, 9442, and 4140, as Well as other alloy steels may be treated in accordance with the present invention utilizing the improved quenching mediums and operations of the present case to produce the beneficial effects sought.

EXAMPLE 1 A 1:1 mixture of phosphorus-sulfide reaction product of mahogany sulfonate and mineral oil was diluted with 40 parts by weight of mineral oil and used as a quenching medium for SAE1065 steel bars of /s inch diameter and 36-72 inches in length. The steel was heated to about 1700 F. and quenched from about 1500-1575" F. in the liquid medium for about 4 minutes in order to complete the quenching operation. Hardenability of the metal was determined by the Rockwell C scale and Brinell tests. Improvement in hardness and tensile strength of the metal when using the composition as compared with a prior art base standard quenching oil is illustrated in the following table.

Table I Quenching Rock Brinell Life of Remarks Medium Hard Oil Standard (see 39 363 3 weeks. Warping, de-

below). fOlIDlD g, cracking from 20- v 50%.

1 part modified 47 to 55.- 444 to 555.. 9 months. No dimensional mahoganysulchanges; no Ionate; 40 parts warping, base quenchcracking, or ing oil. deforming; no

surface checks.

EXAMPLE 2 This quenching base consisted of:

7.5 parts by weight of oleic acid 50.0-parts by weight of mahogany sulfonate (of Ex. 1) 42.5 parts by weight of mineral oil it was diluted in the same proportions with mineral oil and used as'a quenching medium for NE 8630 and NE 8650 steel bars under the same conditions as referred to above in the preceding examples. The results obtained are. shown in Table III below for the NE 8630 steel, similarly improved physical properties having been obtained for the NE8650 steel.

EXAMPLE 3 Using similar steel bars 1 inches in diameter, the composition of Example 2 was modified by the addition of minor amounts of oleic acid and triethanolamine to a mixture of mineral oil and mahogany sulfonate of Example 1 and used as a quenching medium under the same conditions as indicated in Examples 1 and 2. Specifically, this quenching composition consisted of:

5.53 parts by weight of oleic acid 3.51 parts by weight of triethanolamine 47.90 parts by weight of mahogany sulfonate of Ex. 1 43.10 parts by weight of mineral oil This base quenching composition was diluted with 10, 20, 50, and 200 parts by weight of mineral oil, and the results obtained are recorded below in Table III.

Likewise improved physical properties were obtained for the NE 8650 steel.

EXAMPLE 4 Modifying the base quenching composition still further by adding an excess of amine, the composition was diluted with mineral oil in the same proportions as indicated in the above examples and used in quenching mediurns for NE 8630 and NE 8650 steel bars under the same conditions as referred to above, and the results shown in Table IV below for the NE 8630. Similarly improved physical properties were obtained for the NE 8650 steel. Specifically, the base quenching composition comprised 5.5 parts by weight of oleic acid 8.5 parts by weight of triethanolamine 45.0 parts by weight of mahogany sulfonate (of Ex. 1) 45.0 parts by weight of mineral oil.

Table IV BQO 1 2 5 10 Surface 36 45 46 46 48 49 1 deep..- 34 41% 42 45 45 44 V4" deep... 33 36 37 41 38V. 38 as deep 30% 33 34 36% 36 35% deep... 30 32% 33 34 35% 34% deep... 29 32% 33% 33 35% 33% )4 deep..- 28 32 32% 33 35% 33 2 Reference to Tables II, III, and IV indicates an overall improvement in hardenability of metals quenched in the compositions of the present invention, even when dilutions of 200 to 1 were used as compared with prior art standard quenching oils and the tables clearly illustrate the improvements obtained. Using 20:1 dilutions of compositions of this invention, for example, Rockwell 0" hardness for NE 8630 steel of from 47 at the surface to 34 at the core, as compared with about 36.5 at the surface and about 28 at the core when using straight quenching oil, is readily obtainable. Improved results were also observed for NE 8650 steel.

When the composition of Examples 1, 2, 3 and 4 is prepared with hydrophilic organic sulfonates in a water medium, corresponding physical properties are materially enhanced without the disadvantages that water alone as a quenching medium would produce. When the respective compositions of Examples 1 through 4 are mixed with water and oil, the corresponding physical properties fall parts of oleic acid 8 parts of triethanolamine 50 parts of organic sulfonate (Example 1) 34 parts of mineral oil 3 parts of sodium acetate 1900 parts of Water Where it is desired to approach those physical properties obtained by the oil quench composition of the present invention, then the quenching medium may be prepared so that the continuous phase is the oil and the discontinuous phase is the Water. Such a composition is illustrated by the following:

EXAMPLE 6 5 parts of oleic acid 3 parts of butylamine 47 parts of organic sulfonate (Example l) 945 parts of mineral oil 1000 parts of water In producing the composition as enumerated above, any desired order of mixing the ingredients may be employed. More particularly the modified sulfonate admixed with oil may be further diluted with the mineral oil component, and the other components then incorporated as desired. Where some materials are soluble in water, they may be dissolved in the water when the latter is used before the water is incorporated with the other components. Emulsions, dispersions and suspensions may be produced by the usual methods from these stated compositions.

An important accomplishment of the present invention is the elimination of quenching cracks, warping, and distortion of metals treated with quenching compositions. Thus the steel bars referred to in Example 1 above, when quenched in a standard quenching medium, resulted in from to 50% rejects due to warping and cracking. Utilizing the compositions of the present invention for quenching baths, this problem is entirely eliminated under actual production conditions for long periods of time.

In Examples 1 through 6 there are shown respective quenching mixtures produced in accordance with the present invention, containing phosphorus-sulfide modified sulfonates, with and without fatty acids, and amines. These compositions are beneficial in modifying the quenching medium when it is mixed with water or oil or a combination of both. In addition, the added components even though they may not materially affect the hardness, as for example, in the case of NE 8650 in which the hardness throughout the 1% inch cross-section of the quenched metal is almost a straight line, act to reduce cracking, checking, Warping to a minimum, and in addition act as inhibitors of oxidation and corrosion and secure stabilization of the mixture.

It should be kept in mind that other factors which are not controllable by quenching mediums, also influence the hardenability of metals. Thus there must be taken into account the thermal diffusivity of the metal which is a thermal property of each individual steel and can be defined as the facility with which heat is transferred within the metal itself at different temperature levels. Furthermore, the uniformity and depth of hardening'depend upon the austenite composition of the metal, the grain size of the austenite, and the amount and distribution of insoluble particles in the austenite. The size of the specimen treated and its surface condition are also important factors which govern the hardenability of the metal. However, considering these inherent factors of the metal as constant, for any particular given metal, the quenching composition of this invention approaches more closely than any known quenching material the ideal results desired in the hardening of metals.

The organic sulfonates and/or mineral oil and/or fatty acids utilized in accordance with this invention may be reacted with phosphorus sulfides such as P285, P453, Pzs'r, etc., and/or reacted with oxidizing agents such as air, potassium permanganate, hydrogen peroxide, phosphorus pentoxide, phosphorus trioxide, phosphorus tetraoxide, ozone, chromates, organic peroxides, such as benzoyl peroxide, lauroyl peroxide, etc., ultra violet rays, X-rays, actinic rays, and other oxidizing agents, in order to impart additional beneficial properties to the quenching medium as well as to the metal treated. Thus the sulfonate, the fatty acid, and the mineral oil may be treated separately or in combination by any of the treatments set forth above, as for example, with phosphorus sulfide at an elevated reaction temperature and the complex reaction base mixture diluted with suitable amounts of mineral oil or water and utilized in accordance with the present invention. The phosphorization and sulfurization treatment may be carried out by heating the stated ingredients or mixtures thereof with any of the stated phosphorus sulfides at elevated temperatures as from 150 to 500 F. for a length of time usually several hours, suflicient to introduce substantial amounts of phosphorus and sulfur into the materials treated or to modify such materials in important directions. The oxidation treatment referred to may be carried out at an elevated temperature, of for example, from about 200 to about 500 F. with any of the stated oxidizing agents for a length of time usually several hours to produce a resulting product which contains combined oxygen in an amount of at least 1%. Or the sulfurization and phosphorization treatment may be applied to the sulfonates or amines or fatty acids or mixtures containing them either in the presence of or in the absence of the mineral oil, and then followed by an oxidation treatment of the character set forth above, or the oxidation treatment may first be applied to any of the stated ingredients or mixtures containing them and then subjected to the phosphorization and sulfurization treatment. Treatments of this character produce complex and far reaching changes in the ingredients that result in materials of particular value for utilization in accordance with the present invention.

To exemplify the production of the phosphorus sulfide reaction products utilizable in accordance with the present invention, the following example is given:

EXAMPLE 7 220 parts of light fraction of mahogany soap such as the alkali metal soap, were heated at a temperature of 212 F. to 660 F. with parts of phosphorus pentasulfide until the evolution of hydrogen sulfide ceased. The resulting product may be used as such in preparing the treating compositions of the examples set forth above. Or it may first be treated with 44 parts of aluminum stearate and maintained at a temperature within the range stated above. In this event the stearate appears to react with execess phosphorus sulfide present. The resulting product may then be utilized for the production of quenching media in accordance with the present invention.

In lieu of phosphorus pentasulfide, equivalent amounts of the other phosphorus sulfides set forth herein may be substituted and reaction products obtained for utilization herein.

In producing any of these products any desired amount of the sulfonate may be replaced by fatty acids particularly higher fatty acids, e. g. from 5% to 70% and the mixtures reacted under the conditions given in Example 7 above. Thus reaction products may be obtained in which the sulfonate is the major component of the reactants or in which the higher fatty acid is the major component reacted with the phosphorizing and sulfurizing agent.

Or in the example given an organic amine may be present in the reaction mixture subjected to the conditions of phosphorization and sulfurization as given in Example 7 above. The organic amine such as triethanolamine or any of the other amines referred to above will usually constitute a minor component of the reaction mixture, e. g. from to 25%, and both higher fatty acid and organic amine may be present in the reaction mixture undergoing treatment under the conditions of Example 7 above. For example the reaction mixture may contain from 50-90% of sulfonate, from 25 to 5% higher fatty acid, and from 25 to 5% of organic amine.

Or any of these components may be reacted separately with the phosphorizing and sulfurizing agent under the conditions of treatment in Example7 to give phosphorized and sulfurized amines, or fatty acids, or sulfonates, which may be utilized then in combinations within the proportions given above.

Since these phosphorized and sulfurized reactants e. g., sulfonates, amines, and fatty acids may be ultimately employed in mineral oil containing compositions, the reaction of the stated reactants may be carried out in the presence of .a mineral oil or a fraction thereof. For example Example 7 may be carried out in the presence of from 10% to 100% of a heavy or light mineral oil fraction under the conditions there set forth. The hydrocarbons will thus be subjected to sulfurization and phosphorization in this way along with the sulfonates. Since the petroleum sulfonates such as mahogany sulfonates may contain residual oil fractions, the oil material present in them may serve for this purpose.

In addition the amine or the fatty acid or both may be present in such reaction mixtures containing oil fraction and sulfonate, subjected to treatment in accordance with the conditions of Example 7 as set forth hereinabove using ratios like those given above to produce very complex products of great utility. Or the amine or fatty acid reaction products with phosphorus sulfides may be made separately in the presence of mineral oil fractions, but under the conditions given in Example 7 and then utilized in various combinations for quenching media. Thus amine or fatty acid may be individually reacted with from 10% to 50% of phosphorus pentasulfide at the temperatures given in Example 7. Or the fatty acid or amine or both may be .added in amounts of from 5 to 25% for example, by weight on the mixture treated, to the reaction product of the sulfonate with P255 in Example 7 where excess P285 is present and heated at the temperatures there given to complete the reactions. Excess fatty acid or organic amine or both may be present and left in the composition for their effects in the quenching medium.

Any of these reaction products of sulfonate, or organic amine, or fatty acid, or mineral oil fractions may constitute separate articles of commerce to be sold and later compounded into the desired quenching media. The addition of organic amines or fatty acids, or both to the final compositions as set forth in examples given above, may be in addition to the presence of their phosphorized and sulfurized derivatives. And any of these phosphorized and sulfurized products as set forth above may be subjected to the oxidation after treatment as taught herein.

The invention has been illustrated by the treatment of steels, alloy steels, etc., as exemplary of the new and unexpected results which are obtainable in the treatment of any metals or their alloys which during processing require a quenching operation. The quenching bath employed will vary within the limits taught herein depending on the metal being treated, the conditions under which it is treated, and the particular effects sought. In general it may be said that in producing compositions suitable by dilution for quenching baths in accordance with the present invention, proportions of ingredients will fall within the following limits in the production of the primary bath; phosphorus-sulfide modified sulfonates, from a fraction of one to one hundred percent; mineral oil or its phosphorus-sulfide reaction product, from a fraction of one percent to about 99%%; fatty acid or its phosphorus sulfide reaction product, from to 60%; and amine or its phosphorus sulfide reaction product from A% to about 40%; the percentages being by weight. The primary baths are then utilized for making the final baths. For steels, the amount of modified sulfonate in the final treatment medium will ordinarily be less than 15% with or Without corresponding amounts of the other additives.

This application is a continuation-in-part of application Serial No. 716,175, filed December 13, 1946, entitled Quenching Steels Patent No. 2,670,310.

Having thus set forth my invention, I claim:

1. The method of hardening steels which are hardenable by heating and quenching which comprises heating such steel to a temperature above its. critical temperature and quenching such heated steel by immersion in a quenching liquid medium containing a minor amount of a sulfur and phosphorus containing reaction product obtained by reacting a phosphorus sulfide at a temperature of from about 212 to 660 F. and an organic sulfonate, the quenching medium being selected from the group consisting of oil, water, and oil-water emulsions.

2. The method of claim 1 in which the quenching medium is a mineral oil fraction.

3. The method of claim 1 in which the quenching medium is a mineral oil-water emulsion.

4. The method of claim 1 in which the sulfonates are oil soluble.

5. The method of claim 1 in which the quenching medium contains minor amounts of a higher fatty acid and of an organic amine.

6. The method of claim 1 in which the quenching medium contains a minor amount of the product obtained by reacting a mineral oil fraction with a phosphorus sulfide at a temperature of from about to 500 F.

7. The method of claim 6 in which the quenching medium contains a minor amount of the product obtained by reacting a higher fatty acid with a phosphorus sulfide at a temperature of from about 150 to 500 F.

8. The method of claim 6 in which the quenching medium contains a minor amount of the product obtained by reacting an organic amine with a phosphorus sulfide at a temperature of from about 150 to 500 F.

9. The method of claim 1 in which the quenching medium contains a minor amount of the product obtained by reacting a higher fatty acid with a phosphorus sulfide at a temperature of from about 150 to 500 F.

10. The method of claim 9 in which the quenching medium contains a minor amount of the product obtained by reacting an organic amine with a phosphorus sulfide at a temperature of from about 150 to 500 F.

11. The method of claim 1 in which the quenching medium contains a minor amount of the product obtained by reacting an organic amine with a phosphorus sulfide at a temperature of from about 150 to 500 F.

12. The method of claim 1 in which the quenching medium includes a minor amount of an organic sulfonate.

13. A quenching oil composition consisting essentially of a quenching medium selected from the group consisting of oil, water, and oil-water emulsions containing a minor amount of a reaction product of an organic sulfonate and a phosphorus sulfide at a temperature of from about 212 to 660 F.

14. The composition of claim 13 which contains minor amounts of a higher fatty acid and of an organic amine.

15. The composition of claim 14 which contains a minor amount of the product obtained by reacting a phosphorus sulfide at a temperature of from about 150 to 500 F. with a mineral oil fraction.

16. The composition of claim 15 which contains a minor amount of the product obtained by reacting a phosphorus sulfide at a temperature of from about 150 to 500 F. with a higher fatty acid.

17. The composition of claim 15 which contains a minor amount of the product obtained by reacting a phosphorus sulfide at a temperature of from about 150 to 500 F. with an organic amine.

18. The composition of claim 13 which contains a minor amount of the product obtained by reacting a phosphorus sulfide at a temperature or" from about 150 to 500 F. with a mineral oil fraction.

19. The composition of 18 which contains a minor amount of the product obtained by reacting a phosphorus sulfide at a temperature of from about 150 to 500 F. with a higher fatty acid.

20. The composition of claim 19 which contains a minor amount of the product obtained by reacting a phosphorus sulfide at a temperature of from about 150 to 500 F. with an organic amine.

21. The composition of claim 13 which contains a minor amount of the product obtained by reacting a phosphorus sulfide at a temperature of from about 150 to 500 F. with a higher fatty acid.

22. The composition of claim 21 which contains a minor amount of the product obtained by reacting a phosphorus sulfide at a temperature of from about 150 to 500 F. with an organic amine.

23. The composition of claim 13 which contains a minor amount of the product obtained by reacting a phosphorus sulfide with an organic amine.

24. The composition of claim 13 in which the quenching medium includes a minor amount of an organic sulfonate.

2,53 6,403 Wallace Jan. 2, 1951 

1. THE METHOD OF HARDENING STEELS WHICH ARE HARDENABLE BY HEATING AND QUENCHING WHICH COMPRISES HEATING SUCH STEEL TO A TEMPERATURE ABOVE ITS CRITICAL TEMPERATURE AND QUENCHING SUCH HEATED STEEL BY IMMERSION IN A QUENCHING LIQUID MEDIUM CONTAINING A MINOR AMOUNT OF A SULFUR AND PHOSPHORUS CONTAINING REACTION PRODUCT OBTAINED BY REACTING A PHOSPHORUS SULFIDE AT A TEMPERATURE OF FROM ABOUT 212 TO 660*F. AND AN ORGANIC SULFONATE, THE QUENCHING MEDIUM SELECTED FROM THE GROUP CONSISTING OF OIL, WATER, AND OIL-WATER EMULSIONS. 